Every day, individuals lose their lives while waiting for organ transplants. The urgency is palpable, not only for those in need of organs but also for the organs themselves, which can swiftly degrade during transit. In an effort to enhance the preservation of human tissues, scientists have shared their findings in ACS’ Nano Letters, where they focus on the potential of fully freezing, instead of merely cooling and then thawing, critical organs. Their study highlights the successful use of a magnetic nanoparticle to rewarm animal tissues.
Every day, individuals lose their lives while waiting for organ transplants. The urgency is palpable, not only for those in need of organs but also for the organs themselves, which can swiftly degrade during transit. In an effort to enhance the preservation of human tissues, scientists have shared their findings in ACS’ Nano Letters, where they focus on the potential of fully freezing, instead of merely cooling and then thawing, critical organs. Their study highlights the successful use of a magnetic nanoparticle to rewarm animal tissues.
As of August 2024, over 114,000 individuals are on the national transplant waiting list in the U.S., per the Organ Procurement and Transplantation Network, with approximately 6,000 dying each year before receiving a transplant. A significant factor in this is the loss of organs during cold storage in transit, particularly when delays result in premature warming. Although techniques have been developed to freeze organs quickly for extended storage without causing damage from ice crystals, these crystals can also form when warming tissues. To overcome this challenge, Yadong Yin and his team have built upon a method known as nanowarming, initiated by collaborator John Bischof, which uses magnetic nanoparticles and magnetic fields to rapidly, uniformly, and safely thaw frozen tissues.
Recently, Yin and his team crafted magnetic nanoparticles, effectively tiny bar magnets, capable of generating heat when subjected to alternating magnetic fields. This heat allowed for the rapid thawing of animal tissues that had been preserved at -238 degrees Fahrenheit (-150 degrees Celsius) within a solution of nanoparticles and a cryoprotective agent. However, the researchers were concerned that uneven distribution of these nanoparticles could lead to overheating in certain areas, potentially resulting in tissue damage and toxicity from the cryoprotective agent at higher temperatures.
To minimize these risks, the researchers continued their exploration, developing a two-stage technique that allows for better control over nanowarming rates. They describe this process in their latest study in Nano Letters:
- Animal tissues or cultured cells were placed in a solution of magnetic nanoparticles combined with a cryoprotective agent and then frozen using liquid nitrogen.
- Initially, an alternating magnetic field started the rapid rewarming of the tissues.
- As the samples neared the melting point of the cryoprotective agent, a horizontal static magnetic field was introduced.
- This second field realigned the nanoparticles, effectively slowing down heat generation.
The reduction of heating speed was most effective in areas rich in nanoparticles, addressing concerns regarding harmful hotspots. When applied to cultured human skin fibroblasts and pig carotid arteries, the researchers observed that cell viability remained high after a few minutes of rewarming, indicating that the thawing process was both swift and safe. The capability to finely regulate tissue rewarming brings us closer to realizing long-term organ cryopreservation, potentially increasing the availability of life-saving transplants for patients, according to the scientists.
The authors express gratitude for the support from the U.S. National Science Foundation.
